I have a Lowrance X-65 and it is doing the same thing. It started getting hard to turn on at the end of last year and then this year it wouldn't come on at all. Found the 3 amp fuse blown. Replaced the fuse and blew another 3 amp. I took it out of my boat and hooked up to a battery and tried a larger fuse. Blew a 5 amp and a 10 amp. I did get it to come on but it wasn't right. The display looks funny and sounds funny also. I'm planning to retire this one, sure it would cost too much to have repaired. I was actually out at Gander Mountain today looking at fish finders to replace it with. I basically just use it for depth so I'll probably replace it with something low budget.
If you find out any info on it, please let me know.